An adverb clause is a group of words that function as an adverb in a sentence. Adverb clauses can be used to add explanatory detail to your writing and explain how or why things happen. To identify adverb clauses, you'll need to understand what an adverb does as well as how a clause is formed.
An adverb is a part of speech that describes an adjective, another adverb or a verb. Adverbs give more information about how an action was performed. In general, they answer questions like, how, why, where and when.
An adverb does this with just one word, but groups of words can also perform this function in sentences. For example:
In each of these sentences, the italicized word or words answer the question how and describe the verb "walked." In the first sentence there is only one adverb, but in the other two sentences, a group of words work together to act as an adverb.
A clause is a group of words that contain both a subject and a verb. This differs from a phrase, which doesn't have a subject and a verb. For example, let's revisit our examples of words being used together as adverbs:
In these examples, "like an old lady" does not contain a subject and a verb, and is, therefore, an adverb phrase. However, "as if she were heading to the gallows" does contain a subject (she) and a verb (were heading), making it an adverb clause.
Clauses can be either independent or dependent. Independent clauses are also called sentences. They can stand alone and express a complete thought. Dependent clauses, or subordinate clauses, cannot stand alone as a complete sentence. For example:
Each of these groups of words has a subject and a verb, but do not form a complete sentence on their own. They are dependent on an independent clause for meaning.
Adverb clauses, also known as adverbial clauses, are dependent clauses that function as adverbs. Since they are dependent clauses, they must have a subordinating conjunction to connect them to the rest of the sentence.
Being able to spot a subordinating conjunction will help you recognize an adverb clause. Below are some examples, which are grouped by what type of adverb question they answer:
Adverb clauses can be placed at the beginning, middle or end of a sentence. When placed at the beginning or in the middle, they require a comma to offset them from the rest of the sentence:
However, when the adverb clause is at the end of a sentence, no comma is needed:
Because they act like adverbs in a sentence, adverb clauses answer the questions where, when, why and how in a sentence. To see how they work, take a look at the examples below:
These adverbial clauses answer the question where.
These adverbial clauses answer the question when.
These adverb clauses answer the question why.
These adverb clauses also answer the question why.
These adverb clauses answer the question how.
These adverb clauses answer the question how, albeit in a roundabout way.
While adverb clauses are a little more complicated than simple adverbs, they are very useful in adding richer detail to your writing by explaining how and why things happen. When you begin to add subordinating conjunctions and dependent clauses to your writing, you add interest by varying the rhythm of your sentences and layering in important information to create a complete picture for the reader.
For more practice, you can see Examples of Adverb Clauses to get a sense of the many ways these descriptors can be used to improve your writing.